Isolating wire bonding in integrated electrical components

ABSTRACT

An electrical component includes a semiconductor layer having a first conductivity type and a interconnect layer disposed adjacent to a frontside of the semiconductor layer. At least one bond pad is disposed in the interconnect layer and formed adjacent to the frontside of the semiconductor layer. An opening formed from the backside of the semiconductor layer and through the semiconductor layer exposes at least a portion of the bond pad. A first region having a second conductivity type extends from the backside of the semiconductor layer to the frontside of the semiconductor layer and surrounds the opening. The first region can abut a perimeter of the opening or alternatively, a second region having the first conductivity type can be disposed between the first region and a perimeter of the opening.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is related to U.S. application Ser. No.12/769,697, entitled “Isolated Wire Bonding in Integrated ElectricalComponents” and filed concurrently herewith.

TECHNICAL FIELD

The present invention relates to integrated electrical components, andmore particularly to isolating wire bonding in integrated electricalcomponents having a semiconductor material overlying a bond pad and awire affixed to the bond pad through an opening in the semiconductormaterial.

BACKGROUND

An image sensor captures images using light-sensitive photosensitiveareas that convert incident light into electrical signals. Image sensorsare generally classified as either front-illuminated image sensors orback-illuminated image sensors. FIG. 1 is a simplified illustration of afront-illuminated image sensor in accordance with the prior art. Imagesensor 100 includes pixels 102, 104, 106 formed within a semiconductorlayer 108 and an interconnect layer 110. Photosensitive areas 112, 114,116 are formed in semiconductor layer 108. Conductive interconnects 118,120, 122, such as gates and connectors, are formed in interconnect layer110.

Unfortunately, the positioning of conductive interconnects 118, 120,122, and various other features associated with interconnect layer 110,over photosensitive areas 112, 114, 116 adversely impacts the fillfactor and quantum efficiency of image sensor 100. This is because light124 from a subject scene must pass through interconnect layer 110 beforeit is detected by photosensitive areas 112, 114, 116.

A back-illuminated image sensor addresses these fill factor and quantumefficiency issues by constructing the image sensor such that light froma subject scene is incident on a backside of the semiconductor layer108. The “frontside” 126 of semiconductor layer 108 is conventionallyknown as the side of semiconductor layer 108 that abuts interconnectlayer 110, while the “backside” 128 is the side of semiconductor layer108 that opposes frontside 126. FIG. 2 is a simplified illustration of aback-illuminated image sensor 200 in accordance with the prior art.Interconnect layer 110 is positioned between support substrate 202 andsemiconductor layer 108. This allows light 124 to strike the backside128 of semiconductor layer 108, where it is detected by photosensitiveareas 112, 114, 116. Light detection by photosensitive areas 112, 114,116 is no longer impacted by the metallization level interconnects andother features of interconnect layer 110.

One of the other features associated with interconnect layer 110 arebond pads. Bond pads are used to transmit signals to, and receivesignals from, various circuits and components in an integratedelectrical component, such as an image sensor. A wire affixed to a bondpad is electrically connected to one or more circuits or components inthe image sensor. FIG. 3 is a graphical illustration of a wire affixedto a bond pad in a back-illuminated image sensor 300 in accordance withthe prior art. Opening 302 is formed through semiconductor layer 304 toexpose a bond pad 306 in interconnect layer 308. If wire 310 contactssemiconductor layer 304 when affixed to bond pad 306, such as at area312, wire 310 is electrically connected to semiconductor layer 304 andproduces an electrical short to the image sensor. The electrical shortrenders the image sensor unusable. Electrical shorts like this are notan issue for front-illuminated image sensors because the bond pads arein the interconnect layer which is positioned above the semiconductorlayer. The bond wire is not able to contact the semiconductor layer.

Electrical shorts can also occur at wafer level testing when a testeraccidentally touches semiconductor layer 304 with a probe pin. Thetester may report the die is faulty when there is no actual problem withthe image sensor.

Failures at both package and wafer testing reduce yield, and henceincrease costs. Several isolation techniques have been used to preventelectrical shorts from damaging the image sensors. FIG. 4 is a graphicaldepiction of a first isolation technique in back-illuminated imagesensors in accordance with the prior art. A conformal insulatingmaterial 400 is deposited over the image sensor and lines the sidewallsof opening 402. The insulating material 400 electrically isolatessemiconductor layer 404 from a wire (not shown). The conformalinsulating material 400, however, narrows the width 406 of opening 402such that in some situations, a wire can not be affixed to bond pad 408because the wire is larger than width 406.

FIG. 5 is a graphical illustration of a second isolation technique inback-illuminated image sensors in accordance with the prior art. Deeptrench isolation regions 500 are formed with dielectric material andextend from the frontside 502 of semiconductor layer 504 to the backside506 of semiconductor layer 504. If wire 508 contacts semiconductor layer504 when affixed to bond pad 510, such as at area 512, deep trenchisolation regions 500 electrically isolate semiconductor layer 504 andprevent wire 508 from producing an electrical short to the image sensor.Unfortunately, the fabrication of deep trench isolation regions is acomplex procedure that requires many processing steps. This complexityincreases the cost to produce image sensors that utilize this isolationtechnique.

SUMMARY

Embodiments of the invention can be implemented in any integratedelectrical component having a semiconductor layer or material overlyinga bond pad and a wire affixed to the bond pad through an opening in thesemiconductor layer or material. An integrated electrical componentincludes a semiconductor layer having a first conductivity type and aninterconnect layer disposed adjacent to a frontside of the semiconductorlayer. At least one bond pad is disposed in the interconnect layer andformed adjacent to the frontside of the semiconductor layer. An openingformed from the backside of the semiconductor layer and through thesemiconductor layer exposes at least a portion of the bond pad. A firstregion having a second conductivity type extends from the backside ofthe semiconductor layer to the frontside of the semiconductor layer andsurrounds the opening. The first region can abut a perimeter of theopening or alternatively, a second region having the first conductivitytype can be disposed between the first region and a perimeter of theopening.

A method for isolating a wire affixed to a bond pad in an electricalcomponent includes forming a first region having a first conductivitytype in a portion of a semiconductor layer having a second conductivitytype. The first region extends from a backside of the semiconductorlayer to a frontside of the semiconductor layer and the firstconductivity type is opposite the second conductivity type. An openingis formed from the backside of the semiconductor layer through thesemiconductor layer to expose at least a portion of a bond pad disposedin an interconnect layer adjacent to the frontside of the semiconductorlayer. A wire can then be affixed to the bond pad.

In one embodiment in accordance with the invention, the first regioncomprises a well and the opening is formed through the well. Theremaining portion of the well surrounds and abuts a perimeter of theopening.

In another embodiment in accordance with the invention, the first regionsurrounds a portion of the semiconductor layer and the opening is formedthrough the surrounded portion of the semiconductor layer. The remainingportion of the surrounded portion of the semiconductor layer abuts aperimeter of the opening and the first region surrounds the opening andabuts the remaining portion of the surrounded portion of thesemiconductor layer.

And in yet another embodiment in accordance with the invention, thefirst region surrounds a portion of the semiconductor layer and a wellof the second conductivity type is formed in the surrounded portion ofthe semiconductor layer. The opening is formed through the well suchthat the remaining portion of the well surrounds and abuts a perimeterof the opening. The first region surrounds the opening and abuts theremaining portion of the well and surrounded portion in thesemiconductor layer.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are better understood with reference to thefollowing drawings. The elements of the drawings are not necessarily toscale relative to each other.

FIG. 1 is a simplified cross-sectional illustration of afront-illuminated image sensor according to the prior art;

FIG. 2 is a simplified cross-sectional illustration of aback-illuminated image sensor according to the prior art;

FIG. 3 is a graphical illustration of a wire affixed to a bond pad in aback-illuminated image sensor in accordance with the prior art;

FIG. 4 is a graphical depiction of a first isolation technique inback-illuminated image sensors in accordance with the prior art;

FIG. 5 is a graphical illustration of a second isolation technique inback-illuminated image sensors in accordance with the prior art;

FIG. 6 is a block diagram of an image capture device in an embodiment inaccordance with the invention;

FIG. 7 is a simplified top view of an image sensor suitable for use asimage sensor 606 in an embodiment in accordance with the invention;

FIG. 8 is a schematic of a pixel suitable for use as pixel 704 in imagesensor 606 in an embodiment in accordance with the invention;

FIG. 9 is a graphical depiction of a first isolation technique in anembodiment in accordance with the invention;

FIGS. 10A-10E are cross-sectional views of a bond pad region that areused to depict a method for fabricating the first isolation techniqueshown in FIG. 11 in an embodiment in accordance with the invention;

FIG. 11 is a top view of opening 912 shown in FIG. 10E before wire 916is affixed to bond pad 914 in an embodiment in accordance with theinvention;

FIG. 12 is a graphical illustration of a second isolation technique inan embodiment in accordance with the invention;

FIGS. 13A-13F are cross-sectional views of a bond pad region that areused to depict a method for fabricating the second isolation techniqueshown in FIG. 12 in an embodiment in accordance with the invention; and

FIG. 14 is a top view of opening 1212 shown in FIG. 13F before wire 1218is affixed to bond pad 1214 in an embodiment in accordance with theinvention.

DETAILED DESCRIPTION

Throughout the specification and claims, the following terms take themeanings explicitly associated herein, unless the context clearlydictates otherwise. The meaning of “a,” “an,” and “the” includes pluralreference, the meaning of “in” includes “in” and “on.” The term“connected” means either a direct electrical connection between theitems connected, or an indirect connection through one or more passiveor active intermediary devices. The term “circuit” means either a singlecomponent or a multiplicity of components, either active or passive,that are connected together to provide a desired function. The term“signal” means at least one current, voltage, charge, or data signal.

Additionally, directional terms such as “on”, “over”, “top”, “bottom”,are used with reference to the orientation of the Figure(s) beingdescribed. Because components of embodiments of the present inventioncan be positioned in a number of different orientations, the directionalterminology is used for purposes of illustration only and is in no waylimiting. When used in conjunction with layers of an image sensor waferor corresponding image sensor, the directional terminology is intendedto be construed broadly, and therefore should not be interpreted topreclude the presence of one or more intervening layers or otherintervening image sensor features or elements. Thus, a given layer thatis described herein as being formed on or formed over another layer maybe separated from the latter layer by one or more additional layers.

And finally, the terms “semiconductor layer” and “wafer” are to beunderstood as a semiconductor-based material including, but not limitedto, silicon, silicon-on-insulator (SOI) technology, silicon-on-sapphire(SOS) technology, doped and undoped semiconductors, epitaxial layers orwell regions formed on a semiconductor substrate, and othersemiconductor structures.

Referring to the drawings, like numbers indicate like parts throughoutthe views.

The present invention is described herein with respect to a particularintegrated electrical component, a back-illuminated image sensor. Thoseskilled in the art will appreciate that the use of embodiments of thepresent invention is not limited to back-illuminated image sensors.Embodiments of the present invention can be employed in any electricalcomponent having a semiconductor layer or semiconductor materialoverlying a bond pad and a wire affixed to the bond pad through anopening in the semiconductor layer. FIG. 6 is a block diagram of animage capture device in an embodiment in accordance with the invention.Image capture device 600 is implemented as a digital camera in FIG. 6.Those skilled in the art will recognize that a digital camera is onlyone example of an image capture device that can utilize an image sensorincorporating the present invention. Other types of image capturedevices, such as, for example, cell phone cameras, scanners, and digitalvideo camcorders can be used with the present invention.

In digital camera 600, light 602 from a subject scene is input to animaging stage 604. Imaging stage 604 can include conventional elementssuch as a lens, a neutral density filter, an iris and a shutter. Light602 is focused by imaging stage 604 to form an image on image sensor606. Image sensor 606 captures one or more images by converting theincident light into electrical signals. Image sensor 606 is implementedas a back-illuminated x-y addressable image sensor in an embodiment inaccordance with the invention. One example of an x-y addressable imagesensor is a Complementary Metal Oxide Semiconductor (CMOS) image sensor.

Digital camera 600 further includes processor 608, memory 610, display612, and one or more additional input/output (I/O) elements 614.Although shown as separate elements in the embodiment of FIG. 6, imagingstage 604 may be integrated with image sensor 606, and possibly one ormore additional elements of digital camera 600, to form a camera module.For example, a processor or a memory may be integrated with image sensor606 in a camera module in embodiments in accordance with the invention.

Processor 608 may be implemented, for example, as a microprocessor, acentral processing unit (CPU), an application-specific integratedcircuit (ASIC), a digital signal processor (DSP), or other processingdevice, or combinations of multiple such devices. Various elements ofimaging stage 604 and image sensor 606 may be controlled by timingsignals or other signals supplied from processor 608.

Memory 610 may be configured as any type of memory, such as, forexample, random access memory (RAM), read-only memory (ROM), Flashmemory, disk-based memory, removable memory, or other types of storageelements, in any combination. A given image captured by image sensor 606may be stored by processor 608 in memory 610 and presented on display612. Display 612 is typically an active matrix color liquid crystaldisplay (LCD), although other types of displays may be used. Theadditional I/O elements 614 may include, for example, various on-screencontrols, buttons or other user interfaces, network interfaces, ormemory card interfaces.

It is to be appreciated that the digital camera shown in FIG. 6 maycomprise additional or alternative elements of a type known to thoseskilled in the art. Elements not specifically shown or described hereinmay be selected from those known in the art. As noted previously, thepresent invention may be implemented in a wide variety of image capturedevices. Also, certain aspects of the embodiments described herein maybe implemented at least in part in the form of software executed by oneor more processing elements of an image capture device. Such softwarecan be implemented in a straightforward manner given the teachingsprovided herein, as will be appreciated by those skilled in the art.

Referring now to FIG. 7, there is shown a simplified top view of animage sensor suitable for use as image sensor 606 in an embodiment inaccordance with the invention. As described earlier, image sensor 700 isimplemented as a back-illuminated image sensor. Image sensor 700includes an imaging area 702 having pixels 704 that are used to captureimages. Pixels 704 can be arranged in any design or pattern, such as,for example, in rows and columns that form an array. Each pixel 704 caninclude a photosensitive area (not shown in FIG. 7) that converts lightinto an electrical charge representative of the amount of light receivedby the photosensitive area. Each pixel can further include one or moreelectrical components or circuits (not shown) that are used to output anelectrical signal representative of the amount of electrical chargecollected by the photosensitive area. An exemplary architecture for apixel is described in more detail in conjunction with FIG. 8.

Image sensor 700 further includes non-imaging area 706. Non-imaging area706 is disposed outside of and surrounding imaging area 702, andincludes circuits and components that sample, read out, and processcorresponding image data from imaging area 702 in an embodiment inaccordance with the invention. The circuits and components innon-imaging area 706 can also provide one or more signals associatedwith sampling, reading out, and processing the image data. By way ofexample only, in a Complementary Metal Oxide Semiconductor (CMOS) imagesensor non-imaging area 706 can include row and column addressingcircuits, digital logic, memory, timing generators, sample and holdcircuits, correlated double sampling, and analog or digital outputcircuits.

Functionality associated with the sampling and read out of imaging area702 and the processing of corresponding image data may be implemented atleast in part in the form of software that is stored in memory 610 andexecuted by processor 608 (see FIG. 6). Portions of the sampling andread out circuitry may be arranged external to image sensor 606, orformed integrally with imaging area 702, for example, on a commonintegrated circuit with photosensitive areas and other elements ofimaging area 702. Those skilled in the art will recognize that otherperipheral circuitry configurations or architectures can be implementedin other embodiments in accordance with the invention.

Image sensor 700 also includes bond pads 708. Bond pads 708 arepositioned outside of, and surround non-imaging area 706 in anembodiment in accordance with the invention. Bond pads 708 can besituated in different locations in other embodiments in accordance withthe invention. Bond pads 708 permit one or more signals to betransmitted to, or received from image sensor 700. Each bond pad 708 canbe electrically connected to a circuit or component in non-imaging area706 or in imaging area 702.

FIG. 8 is a schematic of a pixel suitable for use as pixel 704 in imagesensor 606 in an embodiment in accordance with the invention. Pixel 800includes photosensitive area 802, transfer gate 804, charge-to-voltageconversion mechanism 806, amplifier 808, reset transistor 810, potentialV_(DD) 812, and row select transistor 814, whose drain is connected tothe source of amplifier 808 and whose source is connected to output line816. The drains of reset transistor 810 and amplifier 808 are maintainedat potential V_(DD) 812. The source of reset transistor 810 and the gateof amplifier 808 are connected to charge-to-voltage conversion mechanism806.

Photosensitive area 802 converts light into an electrical charge inresponse to light striking photosensitive area 802. The amount of chargecollected by photosensitive area 802 depends on the amount of light thatfalls on photosensitive area 802, in terms of both intensity andduration. At the end of an integration period for photosensitive area802, the accumulated charge is transferred to charge-to-voltageconversion mechanism 806 using transfer gate 804. Charge-to-voltageconversion mechanism 806 converts the charge into a voltage.Charge-to-voltage conversion mechanism 806 is configured as a floatingdiffusion in an embodiment in accordance with the invention.

Reset transistor 810 resets pixel 800 by setting charge-to-voltageconversion mechanism 806 to potential V_(DD) 812. Amplifier 808amplifies the voltage in charge-to-voltage conversion mechanism 806.Amplifier 808 is implemented as a source follower transistor in anembodiment in accordance with the invention. Row select transistor 814is used to select a row or line of pixels. When row select transistor814 is active, the voltage on amplifier 808 is transferred to outputline 816 and subsequently read out from the pixel array and the imagesensor.

Pixels in other embodiments in accordance with the invention may beimplemented differently from pixel 800. By way of example only, a pixelmay omit one or more elements, such as charge-to-voltage conversionmechanism 806, or share elements in other embodiments in accordance withthe invention. Exemplary alternative pixel architectures are disclosedin U.S. Pat. Nos. 5,949,061, 6,107,655, and 6,218,656.

Referring now to FIG. 9, there is shown a graphical depiction of a firstisolation technique in an embodiment in accordance with the invention.Electrical component 900, illustrated as a back-illuminated imagesensor, includes semiconductor layer 902 and interconnect layer 904. Inthe embodiment shown in FIG. 9, semiconductor layer 902 is formed with asemiconductor material having a p-type conductivity.

Region 906 having an n-type conductivity is formed in semiconductorlayer 902. Region 906 extends from the backside 908 of semiconductorlayer 902 to the frontside 910 of semiconductor layer 902. Opening 912is formed through semiconductor layer 902 to expose at least a portionof bond pad 914. Region 906 surrounds and abuts a perimeter of opening912 in an embodiment in accordance with the invention.

Wire 916 is affixed or connected to bond pad 914 using techniques knownin the art. When wire 916 contacts semiconductor layer 902, such as atarea 918, n-type region 906 and p-type semiconductor layer 902 form areverse biased diode that prevents an electrical short by electricallyisolating contact area 918 from semiconductor layer 902.

FIGS. 10A-10E are cross-sectional views of a bond pad region that areused to depict a method for fabricating the first isolation techniqueshown in FIG. 9 in an embodiment in accordance with the invention. Forthe sake of clarity, only the processes used to form the structure ofFIG. 9 are described. Those skilled in the art will recognize thatadditional manufacturing processes can be performed in addition to theones described herein, or additional components in an image sensor canbe formed simultaneously with the processes described herein.

Initially, a masking layer 1000 is deposited on the frontside 910 ofsemiconductor layer 902 and patterned to form opening 1002 (see FIG.10A). N-type dopants are then implanted (as represented by the arrows)into semiconductor layer 902 to form n-type well 1004.

Next, as shown in FIG. 10B, masking layer 1000 is removed and adielectric material that forms interconnect layer 904 is deposited onthe frontside 910 of semiconductor layer 902. Interconnect layers 1006,1008, 1010 and bond pad 914 are formed in interconnect layer 904 usingtechniques known in the art.

Semiconductor layer 902 and interconnect layer 904 are then flipped overor rotated one hundred and eighty degrees and interposer wafer 1012affixed to interconnect layer 904 (see FIG. 10C). Interposer wafer 1012is affixed to interconnect layer 904 using one or more techniques knownin the art. The backside 908 of semiconductor layer 902 is then thinneduntil semiconductor layer 902 is at a given thickness (T). Semiconductorlayer 912 can be thinned using techniques known in the art.

Next, as shown in FIG. 10D, a masking layer 1014 is deposited over thebackside 908 of semiconductor layer 902 and patterned to form opening1016. Opening 912 is then formed through n-type well 1004 insemiconductor layer 902 to expose a portion of bond pad 914. Opening 912can be formed in semiconductor layer 902 using techniques known in theart. The portion of n-type well 1004 that remains in semiconductor layer902 forms region 906 that surrounds and abuts the perimeter of opening912.

Masking layer 1014 is then removed and wire 916 affixed or connected tobond pad 914, as shown in FIG. 10E. Although FIGS. 10A-10E depict region906 with an n-type conductivity and semiconductor layer 902 with ap-type conductivity, other embodiments can form region 906 with a p-typeconductivity and semiconductor layer 902 with an n-type conductivity.

Referring now to FIG. 11, there is shown a top view of opening 912 shownin FIG. 10E before wire 916 is affixed to bond pad 914 in an embodimentin accordance with the invention. Opening 912 exposes at least a portionof bond pad 914. Region 906 surrounds and abuts the perimeter of opening912. Semiconductor layer 902 surrounds and abuts region 906. Althoughopening 912, region 906, and semiconductor layer 902 are each depictedin FIG. 11 as having a rectangular shape, those skilled in the art willrecognize that opening 912, region 906, or semiconductor layer 902 caneach have any given shape.

FIG. 12 is a graphical depiction of a second isolation technique in anembodiment in accordance with the invention. Electrical component 1200,illustrated as a back-illuminated image sensor, includes semiconductorlayer 1202 and interconnect layer 1204. In the embodiment shown in FIG.12, semiconductor layer 1202 is formed with a semiconductor materialhaving a p-type conductivity.

Region 1206 having an n-type conductivity is formed in semiconductorlayer 1202. Region 1206 extends from the backside 1208 of semiconductorlayer 1202 to the frontside 1210 of semiconductor layer 1202. Opening1212 is formed through semiconductor layer 1202 to expose at least aportion of bond pad 1214. Region 1206 surrounds but does not abut theperimeter of opening 1212 in an embodiment in accordance with theinvention. Instead, region 1216 having a p-type conductivity ispositioned between region 1206 and the perimeter of opening 1212. Region1216 can have the same dopant type and dopant concentration assemiconductor layer 1202, or region 1216 can include a different dopantor a different dopant concentration than semiconductor layer 1202.

Wire 1218 is connected to bond pad 1214. When wire 1218 contactssemiconductor layer 1202, such as at area 1220, p-type region 1216,n-type region 1206, and p-type semiconductor layer 1202 prevent wire1218 from producing an electrical short to semiconductor layer 1202.

FIGS. 13A-13E are cross-sectional views of a bond pad region that areused to depict a method for fabricating the second isolation techniqueshown in FIG. 12 in an embodiment in accordance with the invention. Forthe sake of clarity, only the processes used to form the structure ofFIG. 12 are described. Those skilled in the art will recognize thatadditional manufacturing processes can be performed in addition to theones described herein, or additional components in an image sensor canbe formed simultaneously with the processes described herein.

Initially, a masking layer 1300 is deposited on the frontside 1210 ofsemiconductor layer 1202 and patterned to form opening 1302 (see FIG.13A). N-type dopants are then implanted (as represented by the arrows)into semiconductor layer 1202 to form n-type region 1206. N-type region1206 surrounds a portion 1303 of semiconductor layer 1202.

Next, as shown in FIG. 13B, masking layer 1300 is removed and anothermasking layer 1304 deposited on frontside 1210 and patterned to formopening 1306. P-type dopants are then implanted (as represented by thearrows) into the enclosed portion 1303 of semiconductor layer 1202 toform p-type well 1308. The processes illustrated in FIG. 13B areoptional and well 1308 is not formed in another embodiment in accordancewith the invention. Instead, the p-type semiconductor material in theenclosed portion 1303 of semiconductor layer 1202 is not doped withadditional p-type dopants.

Masking layer 1304 is then removed and dielectric material that formsinterconnect layer 1204 is deposited on the frontside 1210 ofsemiconductor layer 1202 (see FIG. 13C). Interconnect layers 1310, 1312,1314 and bond pad 1214 are formed in interconnect layer 1204 usingtechniques known in the art.

Next, as shown in FIG. 13D, semiconductor layer 1202 and interconnectlayer 1204 are flipped over or rotated one hundred and eighty degreesand interposer wafer 1316 affixed to interconnect layer 1204. Interposerwafer 1316 is affixed to interconnect layer 1204 using one or moretechniques known in the art. The backside 1208 of semiconductor layer1202 is then thinned until semiconductor layer 1202 is at a giventhickness (T). Semiconductor layer 1202 can be thinned using techniquesknown in the art.

A masking layer 1318 is then deposited over backside 1208 and patternedto form opening 1320 (see FIG. 13E). Opening 1212 is formed throughp-type well 1308 in semiconductor layer 1202 to expose a portion of bondpad 1214. The portion of p-type well 1308 that remains in semiconductorlayer 1202 forms region 1216 that surrounds and abuts the perimeter ofopening 1212.

Next, as shown in FIG. 13F, masking layer 1318 is removed and wire 1218affixed or connected to bond pad 1214. Although FIGS. 13A-13F depictregion 1216 and semiconductor layer 1202 with a p-type conductivity andregion 1206 with an n-type conductivity, other embodiments in accordancewith the invention can form semiconductor layer 1202 and region 1216with an n-type conductivity and region 1206 with a p-type conductivity.

Referring now to FIG. 14, there is shown a top view of opening 1212shown in FIG. 13F before wire 1218 is affixed to bond pad 1214 in anembodiment in accordance with the invention. Opening 1212 exposes atleast a portion of bond pad 1214. Region 1216 surrounds and abuts theperimeter of opening 1212. Region 1216 can be produced using a dopedwell formed in semiconductor layer 1202 (see FIG. 13B) or with thesemiconductor material in semiconductor layer 1202. Region 1206surrounds region 1216, or surrounds a portion of semiconductor layer1202 when a doped well is not fabricated in semiconductor layer 1202. Inthe embodiment shown in FIG. 14, region 1206 surrounds region 1216.

Semiconductor layer 1202 surrounds and abuts region 1206. Althoughopening 1212, region 1216, region 1206, and semiconductor layer 1202 areeach depicted in FIG. 14 as having a rectangular shape, those skilled inthe art will recognize that opening 1212, region 1216, region 1206, orsemiconductor layer 1202 can each have any given shape.

Embodiments of the present invention advantageously provide a lesscomplex technique for isolating a wire bonded to a bond pad through anopening in a semiconductor layer or material. Embodiments of the presentinvention are also less costly to produce and improve performance andtesting conditions for the electrical components.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention. For example, the embodiments shown in FIGS. 9-14 aredescribed with reference to particular conductivity types. Theconductivity types can be different in other embodiments in accordancewith the invention. And as discussed earlier, embodiments of theinvention are not limited to image sensors. The present invention can beimplemented in any electrical component having a semiconductor layer ormaterial overlying a bond pad and a wire affixed to the bond pad throughan opening in the semiconductor layer or material.

Additionally, even though specific embodiments of the invention havebeen described herein, it should be noted that the application is notlimited to these embodiments. In particular, any features described withrespect to one embodiment may also be used in other embodiments, wherecompatible. And the features of the different embodiments may beexchanged, where compatible.

PARTS LIST

-   100 front-illuminated image sensor-   102 pixel-   104 pixel-   106 pixel-   108 semiconductor layer-   110 interconnect layer-   112 photosensitive area-   114 photosensitive area-   116 photosensitive area-   118 conductive interconnect-   120 conductive interconnect-   122 conductive interconnect-   124 light-   126 frontside of semiconductor layer-   128 backside of semiconductor layer-   200 back-illuminated image sensor-   202 support substrate-   300 back-illuminated image sensor-   302 opening-   304 semiconductor layer-   306 bond pad-   308 interconnect layer-   310 wire-   312 area where wire contacts semiconductor layer-   400 insulating material-   402 opening-   404 semiconductor layer-   406 width-   408 bond pad-   500 deep trench isolation region-   502 frontside of semiconductor layer-   504 semiconductor layer-   506 backside of semiconductor layer-   508 wire-   510 bond pad-   512 area where wire contacts semiconductor layer-   600 image capture device-   602 light-   604 imaging stage-   606 image sensor-   608 processor-   610 memory-   612 display-   614 other input/output (I/O)-   700 image sensor-   702 imaging area-   704 pixel-   706 non-imaging area-   708 bond pad-   800 pixel-   802 photosensitive area-   804 transfer gate-   806 charge-to-voltage conversion mechanism-   808 amplifier-   810 reset transistor-   812 potential-   814 row select transistor-   816 output line-   900 electrical component-   902 semiconductor layer-   904 interconnect layer-   906 region-   908 backside of semiconductor layer-   910 frontside of semiconductor layer-   912 opening-   914 bond pad-   916 wire-   918 area where wire contacts semiconductor layer-   1000 masking layer-   1002 opening-   1004 well-   1006 interconnect-   1008 interconnect-   1010 interconnect-   1012 interposer wafer-   1014 masking layer-   1016 opening-   1200 electrical component-   1202 semiconductor layer-   1204 interconnect layer-   1206 region-   1208 backside of semiconductor layer-   1210 frontside of semiconductor layer-   1212 opening-   1214 bond pad-   1216 region-   1218 wire-   1220 area where wire contacts semiconductor layer-   1300 masking layer-   1302 opening-   1303 portion of semiconductor layer surrounded by region 1206-   1304 masking layer-   1306 opening-   1308 well-   1310 interconnect-   1312 interconnect-   1314 interconnect-   1316 interposer wafer-   1318 masking layer-   1320 opening

1. A method for isolating a wire affixed to a bond pad in an integratedcircuit device, the method comprising: forming a first region having afirst conductivity type in a portion of a semiconductor layer, thesemiconductor layer having a second conductivity type and having atleast one integrated circuit formed therein, wherein the first regionsurrounds a portion of the semiconductor layer and extends from abackside of the semiconductor layer to a frontside of the semiconductorlayer, and wherein the first conductivity type is opposite the secondconductivity type; forming an opening from the backside of thesemiconductor layer through the semiconductor layer to expose at least aportion of a bond pad disposed in an interconnect layer formed on thefrontside of the semiconductor layer, wherein the first region surroundsthe opening; and forming a well of the second conductivity type in theportion of the semiconductor layer surrounded by the first region. 2.The method as in claim 1, further comprising thinning the semiconductorlayer to a given thickness prior to forming the opening, wherein thefirst region and the well both extend from the backside of the thinnedsemiconductor layer to the frontside of the thinned semiconductor layer.3. The method as in claim 2, wherein forming an opening from a backsideof the semiconductor layer through the semiconductor layer to expose atleast a portion of the bond pad comprises forming an opening through abackside of the semiconductor layer through the well to expose at leasta portion of the bond pad, wherein the remaining portion of the wellabuts and surrounds a perimeter of the opening.
 4. The method as inclaim 1, wherein forming an opening through a backside of thesemiconductor layer through the semiconductor layer to expose at least aportion of the bond pad comprises forming an opening through a backsideof the semiconductor layer through the surrounded portion of thesemiconductor layer to expose at least a portion the bond pad such thatthe first region surrounds the opening but does not abut a perimeter ofthe opening.